feat: add support for external ClickHouse instances#54
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Allow using an external ClickHouse instance (e.g. ClickHouse Cloud) instead of the bundled Helm-managed ClickHouse backed by EFS. This eliminates the need for EFS (~$400/month) for ClickHouse's write-heavy workload. When `clickhouse_deploy = false`, all EFS and ClickHouse PV resources are skipped, and the Helm chart is configured to connect to the external instance. Setting `clickhouse_deploy = true` (default) preserves existing behavior with zero breaking changes. New variables: clickhouse_deploy, clickhouse_host, clickhouse_http_port, clickhouse_native_port, clickhouse_database, clickhouse_user, clickhouse_password, clickhouse_ssl, clickhouse_cluster_enabled. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Steffen911
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Apr 28, 2026
Without these, upgrading an existing deployment would destroy and recreate the EFS file system (losing ClickHouse data), the random ClickHouse password (breaking auth), and related IAM/SG resources when their addresses gain a [0] index.
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Summary
clickhouse_deployvariable (defaulttrue) to toggle between bundled and external ClickHouseclickhouse_deploy = false, skip all EFS and ClickHouse PV/access point resources, and configure the Helm chart to connect to an external ClickHouse instanceclickhouse_host,clickhouse_http_port,clickhouse_native_port,clickhouse_database,clickhouse_user,clickhouse_password,clickhouse_ssl,clickhouse_cluster_enabledclickhouse_deployclickhouse_deploy = truecontinue to work identicallyMotivation
The bundled ClickHouse deployment uses EFS for persistent storage, which incurs ~$400/month due to ClickHouse's write-heavy I/O patterns. Using an external ClickHouse instance (e.g. ClickHouse Cloud) eliminates the need for EFS entirely, significantly reducing costs while improving ClickHouse performance.
Test plan
terraform validatepassesterraform planwithclickhouse_deploy = true(default) shows no resource additions or deletions — only cosmetic Helm values restructuring and automatic[0]index movesterraform planwithclickhouse_deploy = false+ external ClickHouse vars shows EFS/ClickHouse resources removed and Helm values updatedclickhouse_deploy = trueon a live deployment confirming backward compatibility🤖 Generated with Claude Code